Project Malibu Update: We Swap in a 4L60E

When the guys at Trick Flow Specialties sent us out the door last summer with a fresh 350 under hood of our 1978 Malibu, they seemed to be taking bets on how long the transmission would last. “The first half-throttle upshift will kill it,” one of the guys speculated. That comment was met with guffaws, kind wishes for our well being, and the hopes that my AAA policy included plenty of tow-truck miles. I joined in with nervous laughter, knowing that behind that new engine was the stock TH200 transmission.

Not to be confused with the TH200 4R four-speed automatic, the TH200 is more like the TH350’s baby brother. Light duty at best, the transmission was designed to work behind the Malibu’s stock two-barrel 305 that, when new, struggled to make a stingy 110 hp. Now residing behind a 350 built with Trick Flow’s 400hp top-end kit, the diminutive “Metric 200” (as it’s known) was definitely on borrowed time, and our impending cross-country trek could have been Car Craft’s adaptation of The Green Mile, where a misapplication of too much power would surely result in a smoking pile of ruin. Though I laughed along with the guys from Trick Flow, I knew there was more truth than hyperbole in their statements.

Indeed, the transmission did slip on greater-than-half-throttle upshifts, even with the throttle valve cable adjusted properly. For some advice, we spoke with transmission expert Leo Glassbrenner, owner of Remac Transmissions in San Dimas, California. One of his specialties is building drag-race versions of the Metric 200, which are popular in the Stock classes because of their light weight. Lots of parts have to be replaced, however, for them to be dragstrip ready. Glassbrenner told us a street build of the 200 could probably handle about 400 to 450 hp, but above that, it becomes more cost-effective to replace it with a transmission with more performance potential, which is what we decided to do.

Since we also wanted an overdrive, our options were the TH200 4R, the TH700-R4/4L60, the 4L60E and it’s variants (4L65E/4L70E), and the 4L80E. The letter E at the end of these transmissions stands for “electronic,” of course, meaning the transmission would need some sort of computer to run it, as opposed to the “analog” 200 4R and 700-R4. The latter two would have been less complicated to install and get running, but in our quest to modernize older cars, we opted for a 4L60E from Performance Automatic. We brought our car to Don Lee Auto in Rancho Cucamonga, California, for some help with the install. There’s no need to fear the electronics: our new trans installed and wired up easily and worked correctly right out of the box. Let’s see how that went down.

With a forged rotating assembly, 10:1 compression, Trick Flow 195 heads, a hydraulic roller cam with 218/224 degrees duration at 0.050, 0.495/0.502-inch valve lift, and a 110-degree lobe-separation angle, the 350 Summit and Trick Flow built us not only sounds awesome, but easily makes roughly three times the power the original 305 did. It’s a strong runner and the perfect candidate to smoke the stock TH200 transmission.Two months ago, we increased our 350’s output even more with a free-breathing exhaust system that included a pair of Patriot headers and 2½-inch stainless-steel mufflers from JBA. Economically priced and a perfect fit, the exhaust definitely felt like it gave a substantial increase in performance over the original 2-inch single-exhaust system. Normally, we’d quantify such claims with a trip to Westech’s chassis dyno, but with a slipping transmission, a chassis dyno session would have been a pointless endeavor; we would not have gotten an accurate reading and would likely have burned the trans up in the process.The TH200 was in production from 1976–1987 and could be found under the X-body (Nova), G-body, and tellingly, the T-body platform. T-body, you say? Yes, the Chevette used a Metric 200, and that should give you a clear idea of just how light-duty these transmissions are. Sure, you can improve a 200 with a shift kit, deeper transmission pans, and a fluid cooler, but we plan to make more power than a “built” 200 should be expected to handle, so we are going to skip that whole process. A TH350 is a direct-fit replacement, and that’s what most people do when getting rid of the 200. Tim Lee, owner of Don Lee Auto, told us the 200-to-350 swap was so common that it was as if the job was part of the car’s routine maintenance schedule. Wanting overdrive, however, we opted for a 4L60E.Performance Automatic supplied the transmission and everything needed to install it into our Malibu. The kit included a 2,200-rpm stall speed lock-up torque converter, the controller and wiring, a throttle position sensor adaptor for our carburetor, a dipstick, transmission mount, slip yoke, and a fluid cooler. These components are included as part of the company’s Street Smart transmission package, which is basically and entire driveline swap in a box.At Don Lee Auto, we had the 200 out within a couple of hours. The front of the bellhousing is actually wider than the headers, so a little wrestling was needed to extract the transmission. Having access to a lift really helped here. That’s owner Tim Lee and technician Rick Galloway maneuvering the 200 out of the car.The 4L60E is the electronic version of the TH700-R4, which is itself an evolution of the TH350 and the transmission that superseded the iconic three-speed. Because they’re a similar design, the shift linkage was interchangeable in our application. Overall, the 4L60E was 1¾ inches longer than the Metric 200 (30 versus 28¼ inches), so plan on either a new or shortened driveshaft when planning this swap.As mentioned, E stands for “electronic,” meaning these transmissions are fully computer controlled. The round 13-pin connector replaces the 700-R4’s throttle valve cable, providing the interface between the PCM and electronically activated shift solenoids in the valvebody. No more fiddling with TV cable adjustments; changing the shift points and firmness are now just a few twists of a dial away.

We were almost as excited to get rid of the stock crossmember as we were about replacing the transmission. So many cars from this era were saddled with single-exhaust systems that were neither efficient nor did they clean up emissions that much, either. The new one from G-Force has cutouts for a real dual-exhaust system. It fits tight to the floor of the car, mounts in the stock locations, and is incredibly substantial. So solid that you could probably use it to jack the car up.Our transmission came from Performance Automatic with a 2,200-rpm stall speed torque converter already installed, so it was a simple task of bolting everything in place. G-Force sells this adjustable transmission mount, which we used to secure the tailshaft to the crossmember.Performance Automatic includes the Simple Shift controller with its electronic transmission packages. It’s a diminutive thing that manages to control all the inner workings of the transmission and simultaneously relay a lot of information to the driver while the car is running—things like current gear, throttle angle, road speed, converter lock-up, and if any faults or trouble codes are found. All this info can be discerned through the pair of LEDs, which flash, or at different rates of speed and in red or green to indicate the transmissions vitals. It sounds complicated, but is quite simple once you see it in action. The dials can be manipulated on the fly as you’re driving and will change shift firmness, shift points, and when the torque converter locks up.You’ll want to mount the Simple Shift controller somewhere that’s accessible from the driver seat. We ran ours through an existing hole in the firewall where the speedo cable passed through. Not many wiring connections are needed, just a constant 12-volt source, another 12 volts available when the key is on, and a good ground.To operate properly, the controller needs to know the throttle angle and vehicle speed, both of which are factored in to determine when the transmission shifts. The kit included a throttle position adapter for our Holley carburetor. It attached to the throttle linkage at the same spot where the Metric 200’s throttle valve did.This is the other end of the throttle valve, which we were originally trying to mount somewhere way out of sight in the transmission tunnel. It’s good that we didn’t, because you need access to the sensor itself for adjustments that need to be made for any changes to the carburetor settings. If you raise or lower the idle speed, you need to readjust the TPS sensor so there is 1/8-inch preload on the sensor. Because the sensor directly affects the line pressure in the transmission, any slack on the cable will result in line pressure that is too low, which will cause the transmission to slip.Performance Automatic includes a deep transmission pan with its kit, which required about 2½ gallons of Dexron III automatic transmission fluid to fill completely.The only other wiring connections needed are to plug into the vehicle speed sensor and the big, 13-pin round connector entering the transmission. Performance Automatic’s easy-to-follow instructions walk you through a comprehensive initial start-up procedure.Obviously, we needed a shorter driveshaft, and Inland Empire Driveline Services accommodated us by lopping a couple inches off our stock driveshaft, welding on a new slip yoke, and balancing the assembly for us. It fit perfectly and runs with no vibrations.What a difference this transmission change has brought to our granny-spec Malibu! With the original trans and torque converter, it felt like we were funneling power through sludge, but this combination of a higher-stall torque converter and a strong-running transmission adds up to tire-smoking launches and neck-snapping shifts. What’s better is that we can dial the performance up or down from the driver seat. On Westech’s chassis dyno, we put down 321 hp at 5,700 rpm and 387 lb-ft of torque at 3,300 rpm, excellent numbers that verify Trick Flow’s claims of 400 hp (at the crankshaft) out of their combination of parts. Stay tuned as we take on some more suspension work and swap out the spindly 7.5-inch, 10-bolt rear axle. It’s now the weak link in our combination.